Imaging lens and imaging apparatus

ABSTRACT

An imaging lens is constituted by, in order from the object side to the image side: a first lens having a negative refractive power and a concave surface toward the image side; a second lens having a negative refractive power; a third lens having a positive refractive power and a convex surface toward the image side; a fourth lens having a negative refractive power and a concave surface toward the image side; a biconvex fifth lens which is cemented to the fourth lens; and a sixth lens having a negative refractive power and a concave surface toward the object side. Conditional Formula (1) below is satisfied: 
       −1.05&lt; f 12/ f &lt;−0.8  (1).

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to JapanesePatent Application No. 2015-164690 filed on Aug. 24, 2015. The aboveapplication is hereby expressly incorporated by reference, in itsentirety, into the present application.

BACKGROUND

The present disclosure is related to an imaging lens which can befavorably utilized in a vehicle mounted camera, an imaging camera, etc.,and to an imaging apparatus equipped with this imaging lens.

Recently, cameras have been being mounted in automobiles to assistdrivers in confirming blind spots toward the sides and the rear, and todiscriminate automobiles, pedestrians, obstacles, etc. within images inthe vicinity of vehicles. A known imaging lens which is utilizable insuch vehicle mounted cameras is disclosed in Taiwanese PatentPublication No. 201428336, for example. Taiwanese Patent Publication No.201428336 discloses a lens system having a six lens configuration.

SUMMARY

High optical performance is required in vehicle mounted cameras in orderto improve the visibility of imaged regions and to improve the accuracyin discrimination of obstacles and the like. However, correction ofaberrations is insufficient in the lens system disclosed in TaiwanesePatent Publication No. 201428336, and accordingly, there is demand foran imaging lens in which various aberrations are favorably corrected.

The present disclosure has been developed in view of the foregoingcircumstances. The present disclosure provides an imaging lens, in whichaberrations are favorably corrected, as well as an imaging apparatusequipped with this imaging lens.

The imaging lens of the present disclosure consists of, in order fromthe object side to the image side:

a first lens having a negative refractive power and a concave surfacetoward the image side;

a second lens having a negative refractive power;

a third lens having a positive refractive power and a convex surfacetoward the image side;

a fourth lens having a negative refractive power and a concave surfacetoward the image side;

a biconvex fifth lens which is cemented to the fourth lens; and

a sixth lens having a negative refractive power and a concave surfacetoward the object side; and

Conditional Formula (1) below being satisfied:

−1.05<f12/f<−0.8  (1)

wherein f12 is the combined focal length of the first lens and thesecond lens, and f is the focal length of the entire lens system.

Note that it is more preferable for Conditional Formula (1-1) below tobe satisfied.

−1.0<f12/f<−0.85  (2-1)

In the imaging lens of the present disclosure, it is preferable forConditional Formula (2) below to be satisfied. Note that it is morepreferable for Conditional Formula (2-1) below to be satisfied.

0.7<f1/f2<2.0  (2)

0.8<f1/f2<1.2  (2-1)

wherein f1 is the focal length of the first lens, and f2 is the focallength of the second lens.

In addition, it is preferable for the second lens to be of a biconvexshape.

In addition, it is preferable for Conditional Formula (3) below to besatisfied. Note that it is more preferable for Conditional Formula (3-1)below to be satisfied.

−2.8<12/f<−1.3  (3)

−2.5<f2/f<−1.5  (3-1)

wherein f2 is the focal length of the second lens, and f is the focallength of the entire lens system.

In addition, it is preferable for Conditional Formula (4) below to besatisfied. Note that it is more preferable for Conditional Formula (4-1)below to be satisfied.

2.5<f123/f<5.0  (4)

3.0<f123/f<4.5  (4-1)

wherein f123 is the combined focal length of the first lens, the secondlens, and the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (5) below to besatisfied. Note that it is more preferable for Conditional Formula (5-1)below to be satisfied.

2.0<r3f/f<6.0  (5)

2.5<r3f/f<5.0  (5-1)

wherein r3f is the radius of curvature of the surface toward the objectside of the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (6) below to besatisfied. Note that it is more preferable for Conditional Formula (6-1)below to be satisfied.

−2.1<r3r/f<−1.2  (6)

−2.0<r3r/f<−1.45  (6-1)

wherein r3r is the radius of curvature of the surface toward the imageside of the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (7) below to besatisfied. Note that it is more preferable for Conditional Formula (7-1)below to be satisfied.

0.5<r45/f<0.75  (7)

0.55<r45/f<0.7  (7-1)

wherein r45 is the radius of surface of the coupling surface between thefourth lens and the fifth lens, and f is the focal length of the entirelens system.

In addition, it is preferable for Conditional Formula (8) below to besatisfied. Note that it is more preferable for Conditional Formula (8-1)below to be satisfied.

−5.5<f6/f<−2.5  (8)

−5.0<f6/f<−3.0  (8-1)

wherein f6 is the focal length of the sixth lens, and f is the focallength of the entire lens system.

In addition, it is preferable for Conditional Formula (9) below to besatisfied. Note that it is more preferable for Conditional Formula (9-1)below to be satisfied.

0.85<max.|f/fx|<1.2  (9)

0.9<max.|f/fx|<1.1  (9-1)

wherein f is the focal length of the entire lens system, and fx is thefocal length of an xth lens (x is an integer within a range from 1 to6). Note that “max.|f/fx|” means the maximum value from among the valuesof “|f/fr|” for the first lens through the sixth lens.

An imaging apparatus of the present disclosure is characterized by beingequipped with the imaging lens of the present disclosure describedabove.

Note that the above expression “consists of” means that lenses thatpractically have no power, optical elements other than lenses such as astop, a cover glass, and filters, and mechanical components such as lensflanges, a lens barrel, an imaging element, a camera shake correctingmechanism, etc. may be included, in addition to the constituent elementslisted above.

In addition, the surface shapes, the radii of curvature, and the signsof the refractive powers of lenses in the above lens are those which areconsidered in the paraxial region for lenses that include asphericalsurfaces.

The imaging lens of the present disclosure consists of, in order fromthe object side to the image side: the first lens having a negativerefractive power and a concave surface toward the image side; the secondlens having a negative refractive power; the third lens having apositive refractive power and a convex surface toward the image side;the fourth lens having a negative refractive power and a concave surfacetoward the image side; the biconvex fifth lens which is cemented to thefourth lens; and the sixth lens having a negative refractive power and aconcave surface toward the object side; and Conditional Formula (1)below is satisfied. Therefore, it is possible for the imaging lens tofavorably correct various aberrations.

−1.05<f12/f<−0.8  (1)

In addition, the imaging apparatus of the present disclosure is equippedwith the imaging lens of the present disclosure. Therefore, the imagingapparatus of the present disclosure is capable of obtaining imageshaving high image quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional diagram that illustrates the lensconfiguration of an imaging lens according to an embodiment of thepresent disclosure (common with an imaging lens of Example 1).

FIG. 2 is a cross sectional diagram that illustrates the lensconfiguration of an imaging lens according to Example 2 of the presentdisclosure.

FIG. 3 is a cross sectional diagram that illustrates the lensconfiguration of an imaging lens according to Example 3 of the presentdisclosure.

FIG. 4 is a cross sectional diagram that illustrates the lensconfiguration of an imaging lens according to Example 4 of the presentdisclosure.

FIG. 5 is a cross sectional diagram that illustrates the lensconfiguration of an imaging lens according to Example 5 of the presentdisclosure.

FIG. 6 is a collection of diagrams that illustrate various aberrationsof the imaging lens of Example 1.

FIG. 7 is a collection of diagrams that illustrate various aberrationsof the imaging lens of Example 2.

FIG. 8 is a collection of diagrams that illustrate various aberrationsof the imaging lens of Example 3.

FIG. 9 is a collection of diagrams that illustrate various aberrationsof the imaging lens of Example 4.

FIG. 10 is a collection of diagrams that illustrate various aberrationsof the imaging lens of Example 5.

FIG. 11 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 1.

FIG. 12 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 2.

FIG. 13 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 3.

FIG. 14 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 4.

FIG. 15 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 5.

FIG. 16 is a diagram that schematically illustrates an imaging apparatusaccording to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the attached drawings. FIG. 1 is a crosssectional diagram that illustrates the lens configuration of an imaginglens according to an embodiment of the present disclosure. The exampleof the configuration illustrated in FIG. 1 corresponds to theconfiguration of an imaging lens of Example 1 to be described later. InFIG. 1, the left side is the object side, and the right side is theimage side. Note that the aperture stop St illustrated in FIG. 1 doesnot necessarily represent the size or shape thereof, but merelyindicates the position of the aperture stop St along an optical axis Z.In addition, FIG. 1 also illustrates an axial light beam wa and a lightbeam wb at a maximum angle of view.

As illustrated in FIG. 1, this imaging lens is constituted by, in orderfrom the object side to the image side, a first lens L1 having anegative refractive power and a concave surface toward the image side; asecond lens L2 having a negative refractive power; a third lens L3having a positive refractive power and a convex surface toward the imageside; a fourth lens L4 having a negative refractive power and a concavesurface toward the image side; a biconvex fifth lens L5 which iscemented to the fourth lens L4; and a sixth lens L6 having a negativerefractive power and a concave surface toward the object side.

By configuring the imaging lens such that the first lens L1 and thesecond lens L2 are negative lenses while the third lens L3 is a positivelens, a widening of the angle of view can be achieved without generatinghigher order aberrations, and the generation of a large amount ofnegative distortion can be suppressed. Further, by configuring thesurface toward the image side of the first lens L1 to be concave,principal light rays of peripheral light beams, which are refracted bythe surface toward the object side in directions away from the opticalaxis in order to widen the angle of view and to correct negativedistortion, will be prevented from being refracted in directions towardthe optical axis by the surface toward the image side, therebycontributing the correction of distortion. By configuring the surfacetoward the image side of the first lens L1 to be concave in this manner,principal light rays can be caused to enter the third lens L3 whilepreventing the principal light rays from being refracted in directionstoward the optical axis. Therefore, a widening of the angle of view canbe achieved while suppressing the generation of higher order aberrationsand suppressing the generation of a large amount of negative distortion.

In addition, effective correction of chromatic aberrations will becomepossible, by forming the fourth lens L4 and the fifth lens L5 as acemented lens with a coupling surface which is concave toward the imageside.

In addition, negative spherical aberration which is generated from thethird lens L3 through the fifth lens L5 can be corrected, by configuringthe sixth lens L6 to be a negative lens.

Further, the imaging lens of the present disclosure is configured suchthat Conditional Formula (1) below is satisfied. By configuring theimaging lens such that the value of f12/f is not less than or equal tothe lower limit defined in Conditional Formula (1), the combinednegative refractive power of the first lens L1 and the second lens L2can be prevented from becoming excessively weak, which contributes toachieving a widening of the angle of view. In addition, by configuringthe imaging lens such that the value of f12/f is not greater than orequal to the upper limit defined in Conditional Formula (1), thecombined negative refractive power of the first lens L1 and the secondlens L2 can be prevented from becoming excessively strong, that is, theabsolute values of the radii of curvature of the surfaces of theselenses can be prevented from becoming excessively small. As a result,the generation of higher order aberrations can be suppressed. Note thatmore favorable properties can be obtained if Conditional Formula (1-1)below is satisfied.

−1.05<f12/f<−0.8  (1)

−1.0<f12/f<−0.85  (1-1)

wherein f12 is the combined focal length of the first lens and thesecond lens, and f is the focal length of the entire lens system.

The imaging lens of the present embodiment is configured as describedabove. Therefore, a wide angle imaging lens having high resolution as awhole can be realized.

In addition, it is preferable for Conditional Formula (2) below to besatisfied. By distributing the negative refractive power necessary towiden the angle of view between the first lens L1 and the second lens L2such that Conditional Formula (2) is satisfied, light rays that enterfrom wide angles of view can be refracted in a stepwise manner to theaperture stop St, which is positioned at the image side of the secondlens L2. As a result, a widening of the angle of view can be achievedwithout higher order aberrations being generated. In addition, principallight rays of peripheral light beams that enter the third lens L3 afterpassing through the second lens L2 can be prevented from being refractedin a direction toward the optical axis. Therefore, generation of a largeamount of negative distortion can be suppressed. Note that morefavorable properties can be obtained if Conditional Formula (2-1) belowis satisfied.

0.7<f1/f2<2.0  (2)

0.8<f1/f2<1.2  (2-1)

wherein f1 is the focal length of the first lens, and f2 is the focallength of the second lens.

In addition, it is preferable for the second lens L2 to be of abiconcave shape. By adopting this configuration, the angles betweenlight rays that enter the second lens L2 and a line normal to a plane atthe point where the light rays pass through the surface toward theobject side of the second lens L2 can be maintained small. As a result,the generation of a large amount of positive spherical aberration can besuppressed, even in the case that the second lens L2 is imparted with astrong refractive power in order to widen the angle of view and tocorrect distortion.

In addition, it is preferable for Conditional Formula (3) below to besatisfied. By configuring the imaging lens such that the value of f2/fis not less than or equal to the lower limit defined in ConditionalFormula (3), the refractive power of the second lens L2 can be setstrong. As a result, a widening of the angle of view is facilitated.Alternatively, because the configuration will have more retro focusproperties, a comparatively long amount of back focus can be secured. Byincreasing the length of the back focus, insertion of filters and thelike will be facilitated, and preventing the generation of stray lightcaused by reflection at the surface of a sensor (an imaging elementprovided at the image formation plane Sim) will be facilitated. Byconfiguring the imaging lens such that the value of f2/f is not greaterthan or equal to the upper limit defined in Conditional Formula (3), therefractive power of the second lens L2 can be prevented from becomingexcessively strong, thereby preventing drastic refraction of light rays.As a result, the generation of higher order aberrations, particularlywith respect to light rays at peripheral portions, can be suppressed.Note that more favorable properties can be obtained if ConditionalFormula (3-1) below is satisfied.

−2.8<f2/f<−1.3  (3)

−2.5<f2/f<−1.5  (3-1)

wherein f2 is the focal length of the second lens, and f is the focallength of the entire lens system.

In addition, it is preferable for Conditional Formula (4) below to besatisfied. It is necessary for the third lens L3 to correct a largeamount of positive spherical aberration generated at the first lens L1and the second lens L2, while returning principal light rays ofperipheral light beams, which have been refracted by the first lens L1and the second lens L2 in directions away from the optical axis in orderto favorably correct distortion, toward the vicinity of the opticalaxis, to enable favorable correction of various aberrations by thefourth lens L4 and the lenses more toward the image side therefrom. Byconfiguring the imaging lens such that the value of f123/f is not lessthan or equal the lower limit defined in Conditional Formula (4), thepositive refractive power of the third lens L3 can be prevented frombecoming excessively strong, and therefore, spherical aberration can beprevented from being excessively corrected. By configuring the imaginglens such that the value of f123/f is not greater than or equal theupper limit defined in Conditional Formula (4), the positive refractivepower of the third lens L3 can be prevented from becoming excessivelyweak, and light beams can be appropriately refracted toward the opticalaxis. Therefore, light beams of each angle of view can be separated andaberrations can be corrected by the fourth lens L4 and lenses moretoward the image side thereof. As a result, favorable performance can beobtained. Note that more favorable properties can be obtained ifConditional Formula (4-1) below is satisfied.

2.5<f123/f<5.0  (4)

3.0<f123/f<4.5  (4-1)

wherein f123 is the combined focal length of the first lens, the secondlens, and the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (5) below to besatisfied. By configuring the imaging lens such that the value of r3f/fis not less than or equal to the lower limit defined in ConditionalFormula (5), the radius of curvature of the surface toward the objectside of the third lens L3 can be prevented from becoming excessivelysmall. Therefore, an increase in negative distortion can be suppressedwithout causing higher order aberrations to be generated. In addition,by configuring the imaging lens such that the value of r3f/f is notgreater than or equal to the upper limit defined in Conditional Formula(5), the radius of curvature of the surface toward the object side ofthe third lens L3 can be prevented from becoming excessively large.Therefore, principal light rays of peripheral light beams can beprevented from being refracted in directions away from the optical axis.As a result, it will not be necessary to set the radius of curvature ofthe surface toward the image side of the third lens L3 to be excessivelysmall in order to cause the principal light rays of each light beam tobe refracted toward the vicinity of the optical axis. As a result, thegeneration of higher order aberrations can be suppressed. Note that morefavorable properties can be obtained if Conditional Formula (5-1) belowis satisfied.

2.0<r3f/f<6.0  (5)

2.5<r3f/f<5.0  (5-1)

wherein r3f is the radius of curvature of the surface toward the objectside of the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (6) below to besatisfied. Satisfying Conditional Formula (6) causes the principal lightray of each light beam to be refracted toward the vicinity of theoptical axis by the surface toward the image side of the third lens L3,thereby realizing favorable correction of aberrations by the fourth lensL4 through the sixth lens L6. By Conditional Formula (6) beingsatisfied, the principal light ray of each light beam can be returned tothe fourth lens L4 without higher order aberration being generated.Therefore, the aperture stop St can be provided at a position remotefrom an image formation plane, light rays at each angle of view can beseparated and aberrations can be corrected by the lenses toward theimage side of the aperture stop St. As a result, high imagingperformance can be obtained. Note that more favorable properties can beobtained if Conditional Formula (6-1) below is satisfied.

−2.1<r3r/f<−1.2  (6)

−2.0<r3r/f<−1.45  (6−1)

wherein r3r is the radius of curvature of the surface toward the imageside of the third lens, and f is the focal length of the entire lenssystem.

In addition, it is preferable for Conditional Formula (7) below to besatisfied. Satisfying Conditional Formula (7) enables favorablecorrection of aberrations to be realized. By configuring the imaginglens such that the value of r45/f is not less than or equal to the lowerlimit defined in Conditional Formula (7), the radius of curvature of thecoupling surface between the fourth lens L4 and the fifth lens L5 can beprevented from becoming excessively small. Therefore, generation of alarge amount of negative spherical aberration can be prevented. Inaddition, the angles formed by peripheral light rays and lines normal toplanes at the points where the light rays pass through the couplingsurface can be prevented from becoming excessively large. Therefore,favorable correction of lateral chromatic aberration will becomepossible without causing higher order aberrations to be generated. Byconfiguring the imaging lens such that the value of r45/f is not greaterthan or equal to the upper limit defined in Conditional Formula (7), theradius of curvature of the coupling surface between the fourth lens L4and the fifth lens L5 can be prevented from becoming excessively large.Therefore, longitudinal chromatic aberration being insufficientlycorrected can be prevented. In addition, the angles formed by peripherallight rays and lines normal to planes at the points where the light rayspass through the coupling surface can be prevented from becomingexcessively small. Therefore, favorable correction of lateral chromaticaberration will become possible. Note that more favorable properties canbe obtained if Conditional Formula (7-1) below is satisfied.

0.5<r45/f<0.75  (7)

0.55<r45/f<0.7  (7-1)

wherein r45 is the radius of surface of the coupling surface between thefourth lens and the fifth lens, and f is the focal length of the entirelens system.

In addition, it is preferable for Conditional Formula (8) below to besatisfied. By configuring the imaging lens such that the value of f6/fis not less than or equal to the lower limit defined in ConditionalFormula (8), the refractive power of the sixth lens L6 can be preventedfrom becoming excessively strong, and it will become possible to causelight rays, particularly of light beams at peripheral portions, to berefracted away from the optical axis without causing higher orderaberrations to be generated. As a result, the effective diameter of thecemented lens formed by the fourth lens L4 and the fifth lens L5 can bemaintained small. Therefore, the radius of curvature of the couplingsurface can be set small, and favorable correction of variousaberrations will become possible. In addition, by configuring theimaging lens such that the value of f6/f is not greater than or equal tothe upper limit defined in Conditional Formula (8), the refractive powerof the sixth lens L6 can be prevented from becoming excessively weak,and correction of positive spherical aberration will be possible. Inaddition, the refractive power of the coupling surface between thefourth lens L4 and the fifth lens L5 can be increased while correctingnegative spherical aberration which is generated at the couplingsurface. Therefore, favorable correction of aberrations will becomepossible. Note that more favorable properties can be obtained ifConditional Formula (8-1) below is satisfied.

−5.5<f6/f<−2.5  (8)

−5.0<f6/f<−3.0  (8-1)

wherein f6 is the focal length of the sixth lens, and f is the focallength of the entire lens system.

In addition, it is preferable for Conditional Formula (9) below to besatisfied. By configuring the imaging lens such that Conditional Formula(9) is satisfied, by distributing refractive powers appropriately amongeach of the lenses, and by not utilizing materials having highproduction sensitivities that would result in higher order aberrationsbeing generated, a loosening of production tolerances will becomepossible, and production of imaging lenses having small fluctuations inperformance will be facilitated. Note that more favorable properties canbe obtained if Conditional Formula (9-1) below is satisfied.

0.85<max.|f/fx|<1.2  (9)

0.9<max.|f/fx|<1.1  (9-1)

wherein f is the focal length of the entire lens system, and fx is thefocal length of an xth lens (x is an integer within a range from 1 to6). Note that “max.|f/fx|” means the maximum value from among the valuesof “|f/fx|” for the first lens through the sixth lens.

In addition, it is preferable for a protective multiple layer filmcoating to be administered in the case that the present imaging lens isto be utilized in extreme environments. Further, an antireflectioncoating may be administered in addition to the protective coating, inorder to reduce ghost light and the like during utilization of theimaging lens.

In addition, in the case that this imaging lens is applied to an imagingapparatus, it is preferable for a cover glass, prisms, and variousfilters, such as an infrared cutoff filter and a low pass filter, to beprovided between the lens system and an image formation plane Sim,depending on the configuration of the imaging apparatus. Note that thesefilters may be provided among the lenses instead of being providedbetween the lens system and the image formation plane Sim. As a furtheralternative, coatings that exhibit the same effects as these filters maybe administered on the lens surfaces of the lenses.

Next, examples of numerical values of the imaging lens of the presentdisclosure will be described.

First, an imaging lens of Example 1 will be described. FIG. 1 is a crosssectional diagram that illustrates the lens configuration of the imaginglens of Example 1. Note that in FIG. 1 and FIGS. 2 through 5 thatcorrespond to Examples 2 through 5 to be described later, the left sideis the object side and the right side is the image side. In addition,the aperture stops St illustrated in FIGS. 1 through 5 do notnecessarily represent the sizes and shapes thereof, but only thepositions thereof along the optical axis Z.

Basic lens data are shown in Table 1, data related to various items areshown in Table 2, and data related to aspherical surface coefficientsare shown in Table 3 for the imaging lens of Example 1. The meanings ofthe symbols in the tables will be described for Example 1 as an example,but the meanings are basically the same for Examples 2 through 5 aswell.

In the lens data of Table 1, surface numbers that sequentially increasewith the surface of the constituent element most toward the object sidebeing designated as 1 are listed in the column Surface Number; the radiiof curvature of each surface are listed in the column Radius ofCurvature; and distances along the optical axis Z between each surfaceand a surface adjacent thereto are listed in the column Distance. Inaddition, the refractive indices with respect to the d line (wavelength:587.6 nm) of each constituent element are listed in the column nd; andthe Abbe's numbers with respect to the d line (wavelength: 587.6 nm) ofeach constituent element are listed in the column vd.

Here, the signs of the radii of curvature are positive in cases that thesurface shape is convex toward the object side, and negative in casesthat the surface shape is convex toward the image side. Table 1 alsoshows data regarding the aperture stop St. Text reading “(Stop)” isindicated along with a surface number in the column of the surfacenumber at the surface corresponding to the aperture stop.

The values of the focal length f′ of the entire lens system, the backfocus Bf′, the F value F No., and the full angle of view 2ω are shown asdata related to various items in Table 2.

In the basic lens data and the data related to various items, degreesare used as the units for angles and mm are used as the units forlengths. However, it is possible for optical systems to beproportionately enlarged or proportionately reduced and utilized.Therefore, other appropriate units may be used.

In the lens data of Table 1, the surface numbers of aspherical surfacesare appended with the mark “*”, and numerical values that representparaxial radii of curvature are shown as the radii of curvature of theaspherical surfaces. The data related to aspherical surface coefficientsof Table 3 show the surface numbers of the aspherical surfaces, and theaspherical surface coefficients related to these aspherical surfaces.The aspherical surface coefficients are the values of the coefficientsKA and Am (m=3, . . . , 20) in the aspherical surface formula below.

Zd=C·h ²/{1+(1−KA·C ² ·h ²)^(1/2) }+ΣAm·h ^(m)

wherein Zd is the depth of the aspherical surface (the length of anormal line that extends from a point on the aspherical surface at aheight h to a plane perpendicular to the optical axis that contacts theapex of the aspherical surface), h is the height (the distance from theoptical axis), C is the inverse of the paraxial radius of curvature, andKA and Am are aspherical surface coefficients (m=3, . . . , 20).

TABLE 1 Example 1: Lens Data Surface Number Radius of Curvature Distancend νd  1 20.4734 1.5000 1.75500 52.32  2 4.7938 1.9000  *3 −18.35820.7766 1.53409 55.87  *4 3.2853 1.1897  5 8.9279 4.5085 1.71700 47.93  6−5.0292 0.1500  7 (stop) ∞ 1.0108  *8 4.9124 1.1317 1.63360 23.61  *91.9494 3.3347 1.53409 55.87 *10 −5.7128 0.3176 *11 −8.6379 0.99991.63360 23.61 *12 −254.2142 2.9451

TABLE 2 Example 1: Items (d line) f′ 3.12 Bf′ 2.95 F No. 2.08 2ω [°]122.0

TABLE 3 Example 1: Aspherical Surface Coefficients Surface Number 3 4 89 KA −5.0805849E+00 3.5923752E−01 −1.1540757E+00 −4.8483951E−01 A34.8992018E−16 1.2938543E−15 −2.0051297E−17 0.0000000E+00 A42.2186548E−02 4.6115748E−02 −2.0404639E−04 1.1328695E−02 A5−5.7914687E−02 −1.4088254E−01 −3.3988595E−03 −4.8246927E−02 A66.0168484E−02 2.1887231E−01 1.3370773E−02 5.1593916E−02 A7−3.0602647E−02 −1.9301048E−01 −1.6848285E−02 2.6530301E−02 A86.8723190E−03 1.0690938E−01 9.1078448E−03 −7.6449555E−02 A93.2189528E−04 −3.3437871E−02 −3.9229415E−04 4.2621704E−02 A10−5.3353927E−04 4.6858839E−04 −1.7410523E−03 2.0539238E−03 A111.0045497E−04 4.4489595E−03 6.1094575E−04 −1.0712420E−02 A121.9444374E−06 −1.6248931E−03 5.2676088E−05 3.6830262E−03 A13−3.3544870E−06 7.1766534E−05 −7.2790532E−05 2.6224684E−04 A144.2403921E−07 8.9422542E−05 1.0912115E−05 −5.4121569E−04 A151.4163425E−08 −2.0831440E−05 2.8558248E−06 1.1865571E−04 A16−8.3841672E−09 6.5100450E−07 −1.0041659E−06 2.0999119E−05 A176.0674665E−10 3.7113447E−07 3.6228480E−09 −1.1359594E−05 A183.0858192E−11 −7.8298262E−08 2.7616935E−08 5.0731479E−07 A19−5.9852211E−12 9.5908922E−09 −1.7334260E−09 3.0678491E−07 A202.1570408E−13 −5.6167875E−10 −1.5621942E−10 −3.6155090E−08 SurfaceNumber 10 11 12 KA 1.6370630E+00 −9.8193444E+00 −1.0000000E+01 A3−1.4782273E−15 2.0223931E−18 −1.4277065E−17 A4 −9.6862007E−02−7.9869498E−02 −1.1737517E−02 A5 2.5876587E−01 2.1876672E−02−4.1661550E−02 A6 −4.3804370E−01 3.4458855E−02 2.6109202E−02 A74.5629780E−01 −1.0294869E−02 3.5905134E−02 A8 −2.4812403E−01−1.6354867E−02 −2.8230719E−02 A9 2.4097506E−02 4.6599412E−03−1.3335406E−02 A10 4.6908885E−02 6.5980632E−03 1.4157899E−02 A11−2.2172654E−02 −1.3488746E−03 2.7557838E−03 A12 5.1170906E−04−1.7522256E−03 −4.0104542E−03 A13 2.0239326E−03 2.4344545E−04−3.2603078E−04 A14 −4.8327343E−04 2.8980583E−04 6.9406726E−04 A15−7.9906510E−06 −2.6964951E−05 2.0515258E−05 A16 2.3609100E−05−2.9010523E−05 −7.3022736E−05 A17 −5.1416120E−06 1.6704429E−06−5.2321160E−07 A18 1.2307590E−07 1.6133017E−06 4.2901853E−06 A191.4459396E−07 −4.4067564E−08 −8.6987039E−10 A20 −1.7770446E−08−3.8285075E−08 −1.0778801E−07

FIG. 6 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 1. Note that in FIG. 6, diagrams that illustratespherical aberration, astigmatism, distortion, and lateral chromaticaberration are illustrated in this order from the left side of thedrawing sheet. These diagrams illustrate aberrations in a state in whichthe object distance is infinity. The diagrams that illustrate sphericalaberration, astigmatism, and distortion show aberrations with the d line(wavelength: 587.6 nm) as a reference wavelength. The diagram thatillustrates spherical aberration shows aberrations related to the d line(wavelength: 587.6 nm), the C line (wavelength: 656.3 nm), and the Fline (wavelength: 486.1 nm), as a black solid line, a long broken line,and a dotted line, respectively. In the diagram that illustratesastigmatism, aberrations in the sagittal direction and aberrations inthe tangential direction related to the d line are indicated by a solidline and a dotted line, respectively. In the diagram that illustrateslateral chromatic diagram, aberrations related to the C line(wavelength: 656.3 nm) and the F line (wavelength: 486.1 nm) are shownas a long broken line and a dotted line, respectively. In the diagramthat illustrates spherical aberration, “FNo.” denotes the F number. Inthe other diagrams that illustrate the aberrations, co denotes halfangles of view.

FIG. 11 is a collection of diagrams that illustrate transverseaberrations of the imaging lens of Example 1. The diagrams thatillustrate transverse aberration with the d line (wavelength: 587.6 nm)are shown in two columns to the right and left. The diagrams in the leftcolumn illustrate aberrations related to the tangential direction, andthe diagrams in the right column illustrate aberrations related to thesagittal direction. In addition, the transverse aberration diagrams arefor states in which the object distance is infinity. The symbol “ω” inthe transverse aberration diagrams represent half angles of view.

The symbols, the meanings, and the manners in which the various piecesof data are described in the description of Example 1 above are the samefor the examples to be described below unless otherwise noted.Therefore, redundant descriptions will be omitted hereinafter.

Next, an imaging lens of Example 2 will be described. FIG. 2 is a crosssectional diagram that illustrates the lens configuration of the imaginglens of Example 2. Basic lens data are shown in Table 4, data related tovarious items are shown in Table 5, and data related to asphericalsurface coefficients are shown in Table 6 for the imaging lens ofExample 2. In addition, FIG. 7 is a collection of diagrams thatillustrate various aberrations and FIG. 12 is a collection of diagramsthat illustrate transverse aberrations of the imaging lens of Example 2.

TABLE 4 Example 2: Lens Data Surface Number Radius of Curvature DistanceNd νd  1 21.5732 1.5000 1.75500 52.32  2 3.9583 1.9000  *3 −8.41680.7766 1.53409 55.87  *4 6.8498 0.9366  5 13.1042 4.6004 1.71700 47.93 6 −5.0330 0.1500  7 (stop) ∞ 1.1358  *8 4.5986 1.1077 1.63360 23.61  *91.9180 3.1308 1.53409 55.87 *10 −6.2822 0.3140 *11 −8.6290 1.00261.63360 23.61 *12 503980.0784 3.2304

TABLE 5 Example 2: Items (d line) f′ 3.13 Bf′ 3.23 F No. 2.30 2ω [°]121.8

TABLE 6 Example 2: Aspherical Surface Coefficients Surface Number 3 4 89 KA −9.7540913E+00 9.2954523E−01 −1.4033441E+00 −1.0054871E+00 A3−1.7534973E−15 1.2177192E−14 4.6479963E−17 −8.0201587E−16 A43.5580053E−02 5.0800274E−02 −9.1635164E−05 3.3504335E−02 A5−7.7142412E−02 −1.2560385E−01 −2.9042146E−03 −7.8512630E−02 A68.1856901E−02 1.8990095E−01 1.5551424E−02 5.8729902E−02 A7−4.4011525E−02 −1.6488037E−01 −2.0362526E−02 4.7084434E−02 A81.0542915E−02 8.9999021E−02 1.0980104E−02 −9.1655619E−02 A94.9937772E−04 −2.7858418E−02 −3.5480426E−04 4.0970976E−02 A10−9.1045490E−04 5.0537789E−04 −2.1937661E−03 5.9334968E−03 A111.8006624E−04 3.5494706E−03 7.7404526E−04 −1.0969611E−02 A124.1271233E−06 −1.2825593E−03 6.6805410E−05 3.4065757E−03 A13−6.6701399E−06 5.1570212E−05 −9.7393635E−05 1.8417394E−04 A148.6814757E−07 6.8946241E−05 1.5605134E−05 −5.3429973E−04 A153.1378525E−08 −1.4980435E−05 3.9782319E−06 1.4681997E−04 A16−1.9071816E−08 3.0783947E−07 −1.4932335E−06 1.8372799E−05 A171.4858180E−09 2.5552328E−07 8.9648154E−09 −1.3885925E−05 A187.5009302E−11 −4.8714362E−08 4.3137744E−08 8.5835426E−07 A19−1.6294072E−11 6.3809377E−09 −2.7799331E−09 3.7965081E−07 A206.4019669E−13 −4.1799244E−10 −2.6070672E−10 −4.8533285E−08 SurfaceNumber 10 11 12 KA 3.1640530E−01 −1.0000009E+01 −6.8189221E+00 A31.9367763E−15 9.5334139E−18 −1.4853883E−17 A4 −9.8210139E−02−7.5756712E−02 −1.1915383E−02 A5 2.6318123E−01 1.7331125E−02−3.4751604E−02 A6 −4.5327279E−01 2.5276835E−02 1.9314993E−02 A74.6991786E−01 −3.5456310E−03 2.8608992E−02 A8 −2.5327761E−01−1.3327180E−02 −2.0323161E−02 A9 2.4829528E−02 9.8222330E−04−9.5232831E−03 A10 4.7763524E−02 6.6721811E−03 9.5064483E−03 A11−2.3150591E−02 −3.2567356E−04 1.6736399E−03 A12 7.6205264E−04−2.0397429E−03 −2.4717124E−03 A13 2.1295787E−03 8.2375539E−05−1.4888163E−04 A14 −5.3905550E−04 3.7122152E−04 3.9152367E−04 A15−8.2407360E−06 −1.2787132E−05 3.9095434E−06 A16 2.7168098E−05−3.9988878E−05 −3.7932498E−05 A17 −5.5165652E−06 1.0387041E−062.9782412E−07 A18 5.5617570E−08 2.3607735E−06 2.0754408E−06 A191.5626667E−07 −3.3655062E−08 −1.7246222E−08 A20 −1.8023384E−08−5.8880437E−08 −4.9188247E−08

Next, an imaging lens of Example 3 will be described. FIG. 3 is a crosssectional diagram that illustrates the lens configuration of the imaginglens of Example 3. Basic lens data are shown in Table 7, data related tovarious items are shown in Table 8, and data related to asphericalsurface coefficients are shown in Table 9 for the imaging lens ofExample 3. In addition, FIG. 8 is a collection of diagrams thatillustrate various aberrations and FIG. 13 is a collection of diagramsthat illustrate transverse aberrations of the imaging lens of Example 3.

TABLE 7 Example 3: Lens Data Surface Number Radius of Curvature Distancend νd  1 19.3769 1.2300 1.75500 52.32  2 3.6839 1.5000  *3 −6.19530.7814 1.53409 55.87  *4 8.9770 0.7905  5 9.5002 4.6222 1.71700 47.93  6−5.2838 −0.0600  7 (stop) ∞ 1.1525  *8 4.2077 1.0286 1.63360 23.61  *91.8157 3.2657 1.53409 55.87 *10 −5.4101 0.2980 *11 −7.8482 0.73461.63360 23.61 *12 66.1887 3.0550

TABLE 8 Example 3: Items (d line) f′ 3.12 Bf′ 3.06 F No. 2.28 2ω [°]120.8

TABLE 9 Example 3: Aspherical Surface Coefficients Surface Number 3 4 89 KA −9.7438820E+00 3.0847360E+00 −1.3565018E+00 −1.0048200E+00 A3−8.0671836E−16 −1.5079618E−14 −1.3934049E−17 −7.4643415E−16 A45.1933969E−02 7.4930289E−02 1.7162523E−03 3.3607737E−02 A5−1.1111083E−01 −1.6824931E−01 −4.0013800E−03 −7.1777723E−02 A61.1955087E−01 2.3403624E−01 1.4823034E−02 5.3595992E−02 A7−6.7027402E−02 −1.9721228E−01 −1.8330556E−02 4.4265200E−02 A81.7091635E−02 1.1086153E−01 1.0004785E−02 −8.8258715E−02 A97.7776487E−04 −3.8031010E−02 −4.8643886E−04 4.2372209E−02 A10−1.6648099E−03 1.7633615E−03 −1.9666259E−03 4.4953506E−03 A113.6271656E−04 5.1398368E−03 7.1785632E−04 −1.1264224E−02 A126.7419631E−06 −2.0146362E−03 6.0457342E−05 3.7681175E−03 A13−1.5189020E−05 6.2403131E−05 −8.7874901E−05 1.9870063E−04 A142.1444869E−06 1.2099727E−04 1.3048504E−05 −5.8259224E−04 A158.4657216E−08 −2.2960751E−05 3.5652093E−06 1.4917868E−04 A16−5.3054632E−08 −3.4349351E−07 −1.2224705E−06 2.1644559E−05 A174.2160982E−09 4.0964844E−07 2.7603442E−09 −1.4183386E−05 A182.4593307E−10 −5.8958731E−08 3.3940290E−08 7.6025496E−07 A19−5.2794542E−11 1.1613940E−08 −2.2281820E−09 3.8902497E−07 A202.1475929E−12 −1.0886703E−09 −1.8033436E−10 −4.7774775E−08 SurfaceNumber 10 11 12 KA −5.5065889E−01 −9.3759420E+00 −9.9398450E+00 A3−9.3669237E−16 −9.7333568E−18 4.7096188E−18 A4 −1.1345694E−01−1.1130787E−01 −3.7115715E−02 A5 2.5584561E−01 5.9809326E−03−3.9145633E−02 A6 −4.0496531E−01 5.8829681E−02 3.8035044E−02 A74.2675007E−01 4.3873658E−03 2.9009433E−02 A8 −2.3635339E−01−3.0455344E−02 −2.8827989E−02 A9 2.3143774E−02 −2.0853571E−03−8.8366788E−03 A10 4.4153658E−02 1.1855433E−02 1.2079264E−02 A11−2.0320875E−02 3.9943428E−04 1.3461070E−03 A12 3.2343818E−04−2.9786227E−03 −2.9992070E−03 A13 1.8242349E−03 −1.7720150E−05−8.3398530E−05 A14 −4.1927662E−04 4.7175534E−04 4.6643294E−04 A15−7.7206122E−06 −5.5127560E−06 −2.7423962E−06 A16 2.0278792E−05−4.5870022E−05 −4.5000753E−05 A17 −4.4277200E−06 8.3380668E−076.2951627E−07 A18 1.0775476E−07 2.5013295E−06 2.4614776E−06 A191.2271354E−07 −3.4580389E−08 −2.3468810E−08 A20 −1.4898332E−08−5.8425101E−08 −5.8060306E−08

Next, an imaging lens of Example 4 will be described. FIG. 4 is a crosssectional diagram that illustrates the lens configuration of the imaginglens of Example 4. Basic lens data are shown in Table 10, data relatedto various items are shown in Table 11, and data related to asphericalsurface coefficients are shown in Table 12 for the imaging lens ofExample 4. In addition, FIG. 9 is a collection of diagrams thatillustrate various aberrations and FIG. 14 is a collection of diagramsthat illustrate transverse aberrations of the imaging lens of Example 4.

TABLE 10 Example 4: Lens Data Surface Number Radius of CurvatureDistance nd νd  1 22.2220 1.2200 1.75500 52.32  2 3.6043 1.7247  *3−8.0073 0.7100 1.53409 55.87  *4 6.6367 1.0739  5 8.1301 3.9726 1.7170047.93  6 −5.4405 0.4368  7 (stop) ∞ 1.3230  *8 4.4644 0.7000 1.6336023.61  *9 1.9620 3.2494 1.53409 55.87 *10 −4.9715 0.2800 *11 −8.61460.5590 1.63360 23.61 *12 209.6470 3.2017

TABLE 11 Example 4: Items (d line) f′ 2.93 Bf′ 3.20 F No. 2.28 2ω [°]119.6

TABLE 12 Example 4: Aspherical Surface Coefficients Surface Number 3 4 89 KA −9.3851590E+00 −6.1543620E+00 −1.1696276E+00 −8.8931829E−01 A37.8858892E−16 −6.2455731E−16 1.3528746E−16 4.3988682E−16 A44.6582837E−02 6.5975069E−02 4.9322119E−03 3.0023608E−02 A5−6.6942031E−02 −1.1741462E−01 −1.5408806E−02 −6.3238478E−02 A66.5090930E−02 1.7000707E−01 3.0849152E−02 4.3725721E−02 A7−3.5726860E−02 −1.4874607E−01 −3.2426520E−02 3.6388221E−02 A88.8516430E−03 8.0560749E−02 1.7838095E−02 −7.5111589E−02 A93.5350055E−04 −2.4347205E−02 −1.9203904E−03 4.1698063E−02 A10−7.2043080E−04 3.3113842E−04 −3.8010060E−03 3.0557076E−04 A111.3249326E−04 3.0107378E−03 2.1715905E−03 −1.0726727E−02 A124.8904785E−06 −1.0622125E−03 −7.9232758E−05 4.4105575E−03 A13−4.6262032E−06 4.2758069E−05 −3.1512930E−04 1.9308388E−04 A145.1633350E−07 5.5393160E−05 8.2768423E−05 −6.5470688E−04 A152.1415602E−08 −1.1998272E−05 1.5359386E−05 1.3636242E−04 A16−1.0825903E−08 2.5789013E−07 −7.9965579E−06 2.8673344E−05 A178.9313763E−10 1.9896537E−07 2.0570356E−08 −1.2829391E−05 A183.2600821E−11 −3.7366728E−08 2.7867952E−07 3.1761564E−07 A19−9.3112078E−12 4.7991711E−09 −1.4337811E−08 3.4772394E−07 A204.0934404E−13 −3.1188369E−10 −2.5849975E−09 −3.6247201E−08 SurfaceNumber 10 11 12 KA −2.3304536E+00 8.0518613E+00 −3.5334187E+00 A3−2.4490072E−15 6.9657129E−18 3.6986658E−18 A4 −8.2132398E−02−8.7125092E−02 −3.7998609E−02 A5 2.2614111E−01 2.2413396E−02−2.3416409E−02 A6 −4.2189649E−01 4.8714369E−03 2.5952810E−02 A74.4161138E−01 −7.0908031E−03 1.5650304E−02 A8 −2.2696979E−011.3522069E−02 −1.6251510E−02 A9 1.8374232E−02 2.4152410E−03−3.1734590E−03 A10 4.0880215E−02 −7.3833708E−03 6.4074325E−03 A11−1.9411449E−02 −6.9665197E−04 −6.0389388E−05 A12 9.9994399E−042.0423413E−03 −1.5364047E−03 A13 1.7213288E−03 1.4180151E−041.2672463E−04 A14 −5.0296607E−04 −3.3890924E−04 2.3467005E−04 A15−9.3864337E−07 −1.8222588E−05 −2.1298781E−05 A16 2.6367742E−053.3785987E−05 −2.2630441E−05 A17 −4.6694481E−06 1.2842430E−061.5202135E−06 A18 −1.3207337E−07 −1.8659604E−06 1.2534699E−06 A191.2634566E−07 −3.7369794E−08 −4.1319212E−08 A20 −1.0961453E−084.3896599E−08 −3.0105498E−08

Next, an imaging lens of Example 5 will be described. FIG. 5 is a crosssectional diagram that illustrates the lens configuration of the imaginglens of Example 5. Basic lens data are shown in Table 13, data relatedto various items are shown in Table 14, and data related to asphericalsurface coefficients are shown in Table 15 for the imaging lens ofExample 5. In addition, FIG. 10 is a collection of diagrams thatillustrate various aberrations and FIG. 15 is a collection of diagramsthat illustrate transverse aberrations of the imaging lens of Example 5.

TABLE 13 Example 5: Lens Data Surface Number Radius of CurvatureDistance nd νd  1 21.5725 1.6009 1.75500 52.32  2 3.7517 2.0204  *3−8.5780 0.7600 1.53409 55.87  *4 7.2107 0.8682  5 12.9300 4.1751 1.7170047.93  6 −5.0773 0.1712  7 (stop) ∞ 1.0024  *8 4.5078 1.1034 1.6336023.61  *9 1.9478 3.1561 1.53409 55.87 *10 −5.7939 0.3126 *11 −8.32070.8000 1.63360 23.61 *12 852.8847 3.3603

TABLE 14 Example 5: Items (d line) f′ 3.12 Bf′ 3.36 F No. 2.27 2ω [°]123.0

TABLE 15 Example 5: Aspherical Surface Coefficients Surface Number 3 4 89 KA −8.9111457E+00 −7.5961614E−01 −1.3199758E+00 −1.0705994E+00 A3−4.8839225E−16 −3.1856135E−15 −7.7352523E−17 −7.2029523E−16 A43.7462402E−02 5.7526654E−02 1.4482812E−03 3.6232975E−02 A5−8.0450814E−02 −1.4552928E−01 −3.6637928E−03 −7.4921733E−02 A68.4969932E−02 2.2243911E−01 1.3350504E−02 5.1983981E−02 A7−4.6184663E−02 −1.9873186E−01 −1.6861527E−02 4.4130246E−02 A81.1266782E−02 1.1176694E−01 9.2618371E−03 −8.3298211E−02 A95.2154292E−04 −3.5535082E−02 −4.5056496E−04 3.7240451E−02 A10−9.8892217E−04 6.3429990E−04 −1.7710992E−03 5.2191572E−03 A111.9530605E−04 4.7782602E−03 6.3319532E−04 −9.7730428E−03 A125.1787958E−06 −1.7685235E−03 5.3008194E−05 3.0037779E−03 A13−7.3360482E−06 7.2293092E−05 −7.5613670E−05 1.6212359E−04 A149.3480675E−07 1.0038980E−04 1.1285498E−05 −4.5991237E−04 A153.5374393E−08 −2.2365252E−05 2.9954486E−06 1.2512617E−04 A16−2.0873630E−08 4.6977704E−07 −1.0379650E−06 1.5412488E−05 A171.6701934E−09 4.0191453E−07 2.2268515E−09 −1.1592856E−05 A187.9812047E−11 −7.8805252E−08 2.8572214E−08 7.1384527E−07 A19−1.8611545E−11 1.0648555E−08 −1.7842665E−09 3.1036564E−07 A207.6272389E−13 −7.1837940E−10 −1.6046384E−10 −3.9345207E−08 SurfaceNumber 10 11 12 KA 2.4465913E−01 −7.9263603E+00 −8.9894756E+00 A33.6829664E−15 1.5594074E−18 −5.4129126E−18 A4 −9.3270349E−02−7.4027575E−02 −1.4688124E−02 A5 2.4761637E−01 7.2899849E−03−3.8816004E−02 A6 −4.2588293E−01 1.7951186E−02 1.9013422E−02 A74.3280722E−01 3.3076334E−03 3.0791161E−02 A8 −2.2803435E−01−8.2058118E−03 −1.9417264E−02 A9 2.2318007E−02 −1.7281133E−03−1.0265501E−02 A10 4.1660828E−02 4.8164589E−03 9.1604650E−03 A11−2.0333189E−02 3.5577565E−04 1.8342233E−03 A12 8.0785537E−04−1.6254370E−03 −2.3996707E−03 A13 1.8268800E−03 −2.6482754E−05−1.7136155E−04 A14 −4.7336560E−04 3.1196644E−04 3.8175009E−04 A15−6.9122347E−06 −2.1282906E−06 5.8833239E−06 A16 2.3584283E−05−3.4696534E−05 −3.7065268E−05 A17 −4.5137561E−06 4.5680966E−071.9941758E−07 A18 5.2720678E−09 2.0924296E−06 2.0307937E−06 A191.2488219E−07 −2.0113620E−08 −1.5130267E−08 A20 −1.3624605E−08−5.2996685E−08 −4.8210685E−08

Table 16 shows values corresponding to Conditional Formulae (1) through(9) for the imaging lenses of Examples 1 through 5. Note that all of theExamples use the d line as a reference wavelength, and the values shownin Table 16 below are those for the reference wavelength.

TABLE 16 Exam- Exam- Exam- Exam- Exam- Formula Condition ple 1 ple 2 ple3 ple 4 ple 5 (1) f12/f −0.9016 −0.9494 −0.9273 −0.9286 −0.9312 (2)f1/f2 1.6779 0.9593 0.9247 0.8775 0.8673 (3) f2/f −1.6528 −2.2205−2.1583 −2.2774 −2.3152 (4) f123/f 3.1202 3.5820 4.0755 3.8244 4.1513(5) r3f/f 2.8635 4.1880 3.0412 2.7711 2.6092 (6) r3r/f −1.6131 −1.6085−1.6914 −1.8543 −1.7460 (7) r45/f 0.6253 0.6130 0.5812 0.6687 0.6297 (8)f6/f −4.5337 −4.3525 −3.5313 −4.4468 −4.1724 (9) max. | f/fx | 0.97210.9862 1.0342 0.9321 0.9796

As can be understood from the above data, all of the imaging lenses ofExamples 1 through 5 satisfy Conditional Formulae (1) through (9), andare imaging lenses in which various aberrations are favorably corrected.

Next, an imaging apparatus according to an embodiment of the presentdisclosure will be described. Here, an example of a case in which avehicle mounted camera is the embodiment of an imaging apparatus of thepresent disclosure will be described. FIG. 16 is a diagram thatillustrates the manner in which vehicle mounted cameras are mounted onan automobile.

In FIG. 16, an automobile 100 is equipped with an externally mountedcamera 101 for imaging a blind spot range at the side surface on theside of the passenger seat, an externally mounted camera 102 for imaginga blind spot range at the rear side of the automobile 100, and ainternally mounted camera 103 which is mounted on the back surface ofthe rear view mirror and images the same range as the field of view of adriver. The externally mounted camera 101, the externally mounted camera102, and the internally mounted camera 103 are imaging apparatusesaccording to an embodiment of the present disclosure, and are equippedwith imaging lenses according to an embodiment of the present disclosureand imaging elements that convert optical images formed by the imaginglenses into electrical signals. The vehicle mounted cameras of thepresent embodiment (the externally mounted cameras 101 and 102, as wellas the internally mounted camera 103) are equipped with the imaging lensof the present disclosure. Therefore, the vehicle mounted cameras arecapable of obtaining favorable images.

The present disclosure has been described with reference to theembodiments and Examples. However, the present disclosure is not limitedto the above embodiments and Examples, and various modifications arepossible. For example, the numerical values of the radii of curvature,the surface distances, the refractive indices, the Abbe's numbers, etc.of the lens components are not limited to those exemplified in the aboveExamples, and may be different values.

In addition, the imaging apparatus of the present disclosure is also notlimited to a vehicle mounted camera, and may be various other types ofimaging apparatuses, such as a camera for a portable terminal, asurveillance camera, and a digital camera.

What is claimed is:
 1. An imaging lens consisting of, in order from theobject side to the image side: a first lens having a negative refractivepower and a concave surface toward the image side; a second lens havinga negative refractive power; a third lens having a positive refractivepower and a convex surface toward the image side; a fourth lens having anegative refractive power and a concave surface toward the image side; abiconvex fifth lens which is cemented to the fourth lens; and a sixthlens having a negative refractive power and a concave surface toward theobject side; and Conditional Formula (1) below being satisfied:−1.05<f12/f<−0.8  (1) wherein f12 is the combined focal length of thefirst lens and the second lens, and f is the focal length of the entirelens system.
 2. An imaging lens as defined in claim 1, in whichConditional Formula (2) below is satisfied:0.7<f1/f2<2.0  (2) wherein f1 is the focal length of the first lens, andf2 is the focal length of the second lens.
 3. An imaging lens as definedin claim 1, wherein: the second lens is of a biconcave shape.
 4. Animaging lens as defined in claim 1, in which Conditional Formula (3)below is satisfied:−2.8<f2/f<−1.3  (3) wherein f2 is the focal length of the second lens,and f is the focal length of the entire lens system.
 5. An imaging lensas defined in claim 1, in which Conditional Formula (4) below issatisfied:2.5<f123/f<5.0  (4) wherein f123 is the combined focal length of thefirst lens, the second lens, and the third lens, and f is the focallength of the entire lens system.
 6. An imaging lens as defined in claim1, in which Conditional Formula (5) below is satisfied:2.0<r3f/f<6.0  (5) wherein r3f is the radius of curvature of the surfacetoward the object side of the third lens, and f is the focal length ofthe entire lens system.
 7. An imaging lens as defined in claim 1, inwhich Conditional Formula (6) below is satisfied:−2.1<r3r/f<−1.2  (6) wherein r3r is the radius of curvature of thesurface toward the image side of the third lens, and f is the focallength of the entire lens system.
 8. An imaging lens as defined in claim1, in which Conditional Formula (7) below is satisfied:0.5<r45/f<0.75  (7) wherein r45 is the radius of surface of the couplingsurface between the fourth lens and the fifth lens, and f is the focallength of the entire lens system.
 9. An imaging lens as defined in claim1, in which Conditional Formula (8) below is satisfied:−5.5<f6/f<−2.5  (8) wherein f6 is the focal length of the sixth lens,and f is the focal length of the entire lens system.
 10. An imaging lensas defined in claim 1, in which Conditional Formula (9) below issatisfied:0.85<max.|f/fx|<1.2  (9) wherein f is the focal length of the entirelens system, fx is the focal length of an xth lens, and x is an integerwithin a range from 1 to
 6. 11. An imaging lens as defined in claim 1,in which Conditional Formula (1-1) below is satisfied:−1.0<f12/f<−0.85  (1-1).
 12. An imaging lens as defined in claim 2, inwhich Conditional Formula (2-1) below is satisfied:0.8<f1/f2<1.2  (2-1).
 13. An imaging lens as defined in claim 4, inwhich Conditional Formula (3-1) below is satisfied:−2.5<f2/f<−1.5  (3-1).
 14. An imaging lens as defined in claim 5, inwhich Conditional Formula (4-1) below is satisfied:3.0<f123/f<4.5  (4-1).
 15. An imaging lens as defined in claim 6, inwhich Conditional Formula (5-1) below is satisfied:2.5<r36f<5.0  (5-1).
 16. An imaging lens as defined in claim 7, in whichConditional Formula (6-1) below is satisfied:−2.0<r3r/f<−1.45  (6-1).
 17. An imaging lens as defined in claim 8, inwhich Conditional Formula (7-1) below is satisfied:0.55<r45/f<0.7  (7-1).
 18. An imaging lens as defined in claim 9, inwhich Conditional Formula (8-1) below is satisfied:−5.0<f6/f<−3.0  (8-1).
 19. An imaging lens as defined in claim 10, inwhich Conditional Formula (9-1) below is satisfied:0.9<max.|f/fx|<1.1  (9-1).
 20. An imaging apparatus equipped with animaging lens as defined in claim 1.